CN216849947U

CN216849947U - Lateral gallium nitride schottky diode structure with hybrid high-k dielectric field plate

Info

Publication number: CN216849947U
Application number: CN202220590994.7U
Authority: CN
Inventors: 余丽波; 邓颖婷; 郑崇芝
Original assignee: Chengdu Zhida Hechuang Mdt Infotech Ltd
Current assignee: Chengdu Zhida Hechuang Mdt Infotech Ltd
Priority date: 2022-03-18
Filing date: 2022-03-18
Publication date: 2022-06-28
Anticipated expiration: 2032-03-18

Abstract

The utility model discloses a horizontal gallium nitride schottky diode structure with mix high-K dielectric field board, based on gaN-on-Si epitaxial wafer, gaN-on-Si epitaxial wafer has gaN channel layer and passivation layer, and the passivation layer is located the top of gaN channel layer, its characterized in that is equipped with the high-K dielectric layer at the top of passivation layer, is equipped with positive pole schottky metal electrode on one side of the top of gaN-on-Si epitaxial wafer, and the opposite side is equipped with negative pole ohmic metal electrode, positive pole schottky metal electrode bottom extend to in the gaN channel layer, positive pole schottky metal electrode to the direction of negative pole ohmic metal electrode place extend and constitute the metal field board, the metal field board with high-K dielectric layer and SiN passivation layer constitute jointly and mix high-K dielectric field board; the utility model discloses not only have schottky barrier diode's low opening voltage and low on resistance's advantage, can improve reverse breakdown voltage simultaneously, reduce reverse leakage current.

Description

Lateral gallium nitride schottky diode structure with hybrid high-k dielectric field plate

Technical Field

The utility model relates to a semiconductor power integrated circuit technical field, more specifically the horizontal gallium nitride schottky diode structure that says so relates to have mixed high k dielectric field board. A gan lateral schottky barrier diode.

Background

Gallium nitride is one of the representatives of the third generation wide bandgap semiconductor, and is receiving wide attention, and its superior performance is mainly shown in: high critical breakdown electric field, high electron mobility, high two-dimensional electron gas concentration and high-temperature working capacity. The forbidden bandwidth of the GaN material is as high as 3.4eV, 3 times of the forbidden bandwidth of the Si material and 2.5 times of the forbidden bandwidth of the GaAs material, and the intrinsic carrier concentration of the semiconductor material exponentially increases along with the forbidden bandwidth and the temperature, so that the larger the forbidden bandwidth of the semiconductor material is, the smaller the intrinsic carrier concentration is, and the device has very low leakage current. In addition, the gallium nitride material has stable chemical property, high temperature resistance and corrosion resistance, and has inherent advantages in the application fields of high frequency, high power and radiation resistance.

Gallium nitride power semiconductor devices based on AlGaN/GaN heterojunctions have become strong candidates in the field of high efficiency power transfer switch applications due to their low on-resistance, high breakdown voltage, and high switching speed. Among them, lateral gallium nitride schottky barrier diodes (GaN SBDs) have gained much attention because their fabrication process flow is compatible with that of lateral enhancement mode gallium nitride high electron mobility transistors. An ideal lateral schottky barrier diode should possess a low turn-on voltage, low on-resistance, high breakdown voltage and low reverse leakage current.

The conventional gan lateral schottky barrier diode has a lower forward conduction voltage drop, i.e., a lower forward turn-on voltage, due to schottky contact, but also causes problems of a larger reverse leakage current and a lower reverse breakdown voltage. Therefore, it is one of the problems to be solved by the industry to improve the reverse characteristics of the gan lateral schottky barrier diode while maintaining a low turn-on voltage and a low on-resistance.

SUMMERY OF THE UTILITY MODEL

The utility model discloses a solve the problem that proposes in the technical background, provide the horizontal gallium nitride schottky diode structure with mix high-k dielectric field plate. The structure not only has the advantages of low turn-on voltage and low on resistance of the Schottky barrier diode, but also can improve reverse breakdown voltage and reduce reverse leakage current.

The utility model discloses a following technical scheme realizes:

the transverse gallium nitride Schottky diode structure with the mixed high-K dielectric field plate is provided, based on a GaN-on-Si epitaxial wafer, the GaN-on-Si epitaxial wafer is provided with a GaN channel layer and a passivation layer, the passivation layer is positioned above the GaN channel layer, the transverse gallium nitride Schottky diode structure is characterized in that a high-K dielectric layer is arranged at the top of the passivation layer, an anode Schottky metal electrode is arranged on one side of the top of the GaN-on-Si epitaxial wafer, a cathode ohmic metal electrode is arranged on the other side of the top of the GaN-on-Si epitaxial wafer, the bottom of the anode Schottky metal electrode extends into the GaN channel layer, the anode Schottky metal electrode extends towards the direction of the cathode ohmic metal electrode to form a metal field plate, and the metal field plate, the high-K dielectric layer and the SiN passivation layer jointly form the mixed high-K dielectric field plate.

Preferably, the GaN-on-Si epitaxial wafer further includes an AlGaN barrier layer, and the barrier layer is located between the GaN channel layer and the passivation layer.

Preferably, the GaN-on-Si epitaxial wafer further comprises a P-type Si substrate, an AlN nucleating layer, a GaN buffer layer and a GaN channel layer from bottom to top in sequence, and the GaN channel layer is positioned on the top of the GaN buffer layer.

Preferably, the high-K dielectric layer is made of a high-dielectric material.

Preferably, the high dielectric material is Al₂O₃、HfO₂、ZrO₂Or BaTiO₃Any one of them.

Preferably, the thickness of the high-K dielectric layer is 10 nm-50 nm.

Preferably, the passivation layer adopts Si₃N₄The material is prepared.

Preferably, the thickness of the passivation layer is 50 nm-100 nm.

Providing a manufacturing process of the lateral gallium nitride schottky diode structure with the mixed high-k dielectric field plate, which comprises the following steps;

s1: selecting a GaN-on-Si epitaxial wafer with the structure comprising a P-type Si substrate 1, an AlN nucleating layer 2, a GaN buffer layer 3, a GaN channel layer 4, an AlGaN barrier layer 5 and a SiN passivation layer 6 from bottom to top in sequence;

s2: etching a cathode ohmic electrode region on the GaN-on-Si epitaxial wafer, specifically, a heterojunction is arranged between the AlGaN barrier layer 5 and the GaN channel layer 4, the part from the heterojunction to the SiN passivation layer 6 is etched in the environment of SF6+ CHF3 or Cl2+ BCl3, and the etching depth is 500 nm;

s3: sequentially depositing a cathode ohmic metal layer Ti/Al/Ni/Au on the etched cathode ohmic electrode area and rapidly depositing a cathode ohmic metal layer on the etched cathode ohmic electrode area₂And carrying out high-temperature thermal annealing in the environment to form ohmic contact.

S4: HfO deposition by PELAD on top of the SiN passivation layer 6₂A high-K dielectric layer 7;

s5: etching is carried out on the anode region of the GaN-on-Si epitaxial wafer, specifically, etching is carried out in the environment of SF6+ CHF3 or Cl2+ BCl3, the SiN passivation layer 6 and the HfO2 dielectric layer above the cathode are removed, and Ni/Au metal layers are sequentially deposited on the etched anode ohmic electrode region to form an anode Schottky contact and an electrode pad.

Compared with the prior art, the utility model, following advantage and beneficial effect have:

the utility model discloses for the horizontal gallium nitride schottky barrier diode of tradition, the mixed high-K dielectric field board of setting can effectively shield the electric field of positive pole schottky contact department, reduce the electric field peak value intensity here, and the electric field peak value of positive pole schottky contact department has greatly influenced the final reverse breakdown voltage of leakage current size and device that produces when horizontal gallium nitride schottky barrier diode is reverse withstand voltage, adopt the high-K medium also can effectively reduce device surface electric field intensity simultaneously, consequently the invention can guarantee low opening voltage, effectively improve reverse breakdown voltage and reduce reverse leakage current in the time of low on-resistance.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention.

FIG. 1 is a non-limiting schematic diagram of the present invention;

FIG. 2 is a schematic diagram of a conventional lateral GaN Schottky barrier diode;

fig. 3 is a schematic view of the manufacturing process of the present invention.

Description of reference numerals:

1. the GaN-based high-K metal field plate comprises a P-type Si substrate, 2 an AlN nucleating layer, 3 a GaN buffer layer, 4 a GaN channel layer, 5 an AlGaN barrier layer, 6 a passivation layer, 7 a high-K dielectric layer, 8 a cathode ohmic metal electrode, 9 an anode Schottky metal electrode, 10 and a metal field plate.

Detailed Description

To make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the following examples and drawings, and the exemplary embodiments and descriptions thereof of the present invention are only used for explaining the present invention, and are not intended as limitations of the present invention.

Example 1:

as shown in fig. 1, the lateral GaN schottky diode structure with a hybrid high-K dielectric field plate is based on a GaN-on-Si epitaxial wafer, wherein the GaN-on-Si epitaxial wafer has a GaN channel layer 4 and a passivation layer 6, the passivation layer 6 is located above the GaN channel layer 4, a high-K dielectric layer 7 is arranged on the top of the passivation layer 6, an anode schottky metal electrode 9 is arranged on one side of the top of the GaN-on-Si epitaxial wafer, a cathode ohmic metal electrode 8 is arranged on the other side of the top of the GaN-on-Si epitaxial wafer, the bottom of the anode schottky metal electrode 9 extends into the GaN channel layer 4, the anode schottky metal electrode 9 extends towards the direction of the cathode ohmic metal electrode 8 to form a metal field plate 10, and the metal field plate 10, the high-K dielectric layer 7 and the SiN passivation layer 6 together form a hybrid high-K dielectric field plate;

as shown in fig. 2, in the conventional lateral gan schottky diode, the electric field peak is concentrated at the anode schottky barrier edge during reverse voltage withstanding, and high electric field intensity at this position can cause high reverse leakage current, which affects the reliability and even failure of the device, the metal field plate 10, the high-K dielectric layer 7 and the passivation layer 6 in the invention jointly form a hybrid high-K dielectric field plate, which can shield the electric field peak at the anode schottky barrier edge, and based on the gaussian theorem, the generated electric field intensity can be effectively reduced by using a dielectric material with a higher dielectric constant under the same voltage withstanding condition, and further, higher voltage can be borne, so that the lateral gan schottky diode with the hybrid high-K dielectric field plate effectively increases reverse voltage withstanding and reduces reverse leakage compared with the conventional gan schottky diode without losing forward conduction characteristics.

Preferably, the GaN-on-Si epitaxial wafer further comprises an AlGaN barrier layer 5, and the barrier layer 5 is located between the GaN channel layer 4 and the passivation layer 6.

Preferably, the GaN-on-Si epitaxial wafer further comprises a P-type Si substrate 1, an AlN nucleation layer 2, a GaN buffer layer 3, and a GaN channel layer 4 in sequence from bottom to top, and the GaN channel layer 4 is located on top of the GaN buffer layer 3.

Preferably, the high-K dielectric layer is made of a high-dielectric material, the thickness of the high-K dielectric layer is 10 nm-50 nm, and the high-dielectric material is Al₂O₃、HfO₂、ZrO₂Or BaTiO₃Any one of them.

Preferably, the passivation layer 6 is made of Si₃N₄The material is made of 50 nm-100 nm thick.

Specifically, the voltage resistance of the traditional transverse Schottky diode is only about 150V, and the reverse leakage current is up to 1 mA/mm; the reverse withstand voltage of the transverse gallium nitride Schottky diode with the mixed high-K dielectric field plate can reach more than 600V, which is more than 4 times of that of the traditional structure, the reverse leakage current is reduced to below 1 muA/mm, the reverse leakage current is reduced by at least 3 orders of magnitude compared with the traditional structure, and the performance is improved compared with the traditional transverse Schottky diode.

Example 2:

on the basis of embodiment 1, a manufacturing process of a lateral gallium nitride schottky diode structure with a hybrid high-k dielectric field plate is disclosed, which comprises the following steps;

The above-mentioned embodiments, further detailed description of the objects, technical solutions and advantages of the present invention, it should be understood that the above description is only the embodiments of the present invention, and is not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. The transverse gallium nitride Schottky diode structure with the mixed high-K dielectric field plate is based on a GaN-on-Si epitaxial wafer, the GaN-on-Si epitaxial wafer is provided with a GaN channel layer and a passivation layer, the passivation layer is positioned above the GaN channel layer, the transverse gallium nitride Schottky diode structure is characterized in that a high-K dielectric layer is arranged at the top of the passivation layer, an anode Schottky metal electrode is arranged on one side of the top of the GaN-on-Si epitaxial wafer, a cathode ohmic metal electrode is arranged on the other side of the top of the GaN-on-Si epitaxial wafer, the bottom of the anode Schottky metal electrode extends into the GaN channel layer, the anode Schottky metal electrode extends towards the direction of the cathode ohmic metal electrode to form a metal field plate, and the metal field plate, the high-K dielectric layer and the SiN passivation layer jointly form the mixed high-K dielectric field plate.

2. The lateral GaN schottky diode structure with hybrid high-k dielectric field plate of claim 1 wherein the GaN-on-Si epitaxial wafer further comprises an AlGaN barrier layer, the barrier layer being located between the GaN channel layer and the passivation layer.

3. The lateral GaN schottky diode structure with the hybrid high-k dielectric field plate as claimed in claim 2 wherein the GaN-on-Si epitaxial wafer further comprises a P-type Si substrate, an AlN nucleation layer, a GaN buffer layer, a GaN channel layer in sequence from bottom to top, and the GaN channel layer is on top of the GaN buffer layer.

4. The lateral gan schottky diode structure with the hybrid high-K dielectric field plate as described in any of claims 1-3, wherein the high-K dielectric layer is made of a high dielectric material.

5. The lateral gan schottky diode structure with hybrid high-k dielectric field plate of claim 4 in which the high dielectric material is Al₂O₃、HfO₂、ZrO₂Or BaTiO₃Any one of them.

6. The lateral gan schottky diode structure with the hybrid high-K dielectric field plate of claim 5 wherein the high-K dielectric layer has a thickness of 10nm to 50 nm.

7. The lateral gan schottky diode structure with hybrid high-k dielectric field plate of claim 6 wherein the passivation layer is Si₃N₄The material is prepared.

8. The lateral gan schottky diode structure with the hybrid high-k dielectric field plate of claim 7 wherein the passivation layer has a thickness of 50nm to 100 nm.